The aim of study to evaluate possibilities of functional neuroimaging (18F-FDG PET and +H MRS) in diagnosis and treatment evaluation in patients with resistant obsessive-compulsive disorders.

18F-FDG PET was performed in 19 patients with treatment resistant OCD. Besides, single voxel MRS was used to image the heads of the caudate nucleus in 13 patients. Examinations were executed at the time of treatment cancellation in all cases. Moreover 18F-FDG PET and H MRS were carried out during every periods of complex treatment (including psychotherapy, psychosurgery (in all cases) and combined stimulation of the head of caudate nucleus and vagus nerve (in 3 cases). Parameters of stimulation and its duration were defined using neuroimaging data.

Our results show that application of functional neuroimaging in patients with resistant forms of OCD enables to optimize treatment using adequate medicinal therapy and to prove a choice of brain structures-targets for stereotactic effects. Long-term neuropsychiatric monitoring, neuroimaging data and results of neurostimulation allow to advance a hypothesis about three brain levels of OCD formation in contrast to accepted assumption about four symptom dimensions: symmetry/ordering, hoarding, contamination/cleaning, and obsessions/checking.